Different colors for shapes through iterations in Python / Pygame?

Question

I'm new to stackoverflow, but was hoping for a little insight from more advanced programmers. I am switching majors to Computer Science next semester and am taking an intro class learning some beginner's Python programming. I have already finished the program below (the assignment was to make a program that draws ovals on the window surface by filling in some of the professor's code, not too bad at all) but I wanted to add a little something extra: As you can see, I have the color of the ovals set to be random, but it stays the same until the program is restarted entirely i.e. all of the ovals are that particular color for the length of the program. With the code written the way it is, I can't figure out a way to get the color to change for each oval. Keep in mind, this is all for kicks, but if anyone's feeling especially helpful or creative, I'm curious to see what you have to say. Let me know if I can expound on anything. Thanks!

---

import pygame, random, sys

WINDOWWIDTH = 700
WINDOWHEIGHT = 700
BACKGROUNDCOLOR = (150,160,100)
#A different color every run
OVAL_COLOR = (random.randint (0,255),random.randint (0,255),
                    random.randint (0,255))

pygame.init()
windowSurface = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT))
pygame.display.set_caption("Mobile Ovals")

#The draw variable is used later to indicate the mouse is still pressed
ovals = []
completedOvals = []
finished = False
draw = False
startXY = (-1, -1)

while not finished:
    for event in pygame.event.get():
        if event.type == pygame.QUIT or (event.type == pygame.KEYUP and
                    event.key == pygame.K_ESCAPE):
            finished = True

        elif event.type == pygame.KEYDOWN:
            pressed = pygame.key.get_pressed()
            if pressed[pygame.K_F4] and (pressed[pygame.K_LALT] or
                        pressed[pygame.K_RALT]):
                finished  = True

        elif event.type == pygame.MOUSEBUTTONDOWN:
            startXY = event.pos
            draw = True

        elif event.type == pygame.MOUSEBUTTONUP:
            draw = False
            for oval in ovals:
                completedOvals.append (oval)

        if draw == True:
            del ovals [:]

            #The above function ensures only one oval is onscreen at any given time
            endXY = event.pos
            width = (abs(endXY[0]-startXY[0]))
            height = (abs(endXY[1]-startXY[1]))

            #The code below allows the user to drag any direction
            if endXY[0] < startXY[0]:
                left = endXY[0]
            else:
                left = startXY[0]
            if endXY[1] < startXY[1]:
                top = endXY[1]
            else:
                top = startXY[1]

            ovals.append (pygame.Rect (left, top, width, height))

            windowSurface.fill(BACKGROUNDCOLOR)

            for oval in ovals:
                pygame.draw.ellipse(windowSurface, OVAL_COLOR, oval)

            for completedOval in completedOvals:
                pygame.draw.ellipse(windowSurface, OVAL_COLOR, completedOval)

            pygame.display.update()

pygame.quit()

Answer 1

Create a simple Oval() class, that contains it's color, and size.

import pygame
from pygame.locals import * 

class Oval(object):
    """handle, and draw basic ovals. stores Rect() and Color()"""
    def __init__(self, startXY, endXY):
        self.color = Color(random.randint(0,255), random.randint(0,255), random.randint(0,255))
        self.rect = Rect(0,0,1,1)
        self.coord_to_oval(startXY, endXY)

    def draw(self):
        pygame.draw.ellipse(windowSurface, self.color, self.rect)

    def coord_to_oval(self, startXY, endXY):
        width = (abs(endXY[0]-startXY[0]))
        height = (abs(endXY[1]-startXY[1]))

        #The code below allows the user to drag any direction
        if endXY[0] < startXY[0]:
            left = endXY[0]
        else:
            left = startXY[0]
        if endXY[1] < startXY[1]:
            top = endXY[1]
        else:
            top = startXY[1]

        self.rect = Rect(left, top, width, height)

# main loop
while not finished:
    for event in pygame.event.get():
       # events, and creation:
       # ... your other events here ...

       elif event.type == MOUSEBUTTONDOWN:
            startXY = event.pos
            draw = True

        elif event.type ==MOUSEBUTTONUP:
            # on mouseup, create instance.
            endXY = event.pos
            oval_new = Oval(startXY, endXY)
            completedOvals.append(oval_new)

        # draw them:
        for oval in ovals:
                oval.draw()
        for oval in completedOvals:
                oval.draw()

I mostly left out your non-completed ovals. Was that to show the size before clicking?

Answer 2

Your problem is quite simple. You set OVAL_COLOR once. But every time you make reference to the variable OVAL_COLOR, you're not creating a new random color, you're re-using the RGB color that was randomly generated when you created the variable.

Now, the way your program is structured, you maintain a list of all complete ovals that you're re-drawing every time the draw variable is set to true. If you place the OVAL_COLOR variable inside the for loop, you will update the color with every mouse movement, changing the color of the oval being drawn, as well as the color of all the old ovals being re-drawn.

The solution to have a new random oval color is to set the variable OVAL_COLOR when the mouse button goes down. That way, the oval color won't change as you drag the mouse to adjust the oval. But, given the current structure of the program, you'll need to save the oval colors assigned to completed ovals, or you'll still have the oval color change each time.

---

When the mouse button is pressed down, we want a new random color for our circle. Generate a random value, which will be used every time the circle is re-drawn.

    elif event.type == pygame.MOUSEBUTTONDOWN:
        startXY = event.pos
        OVAL_COLOR = (random.randint (0,255),random.randint (0,255),
                            random.randint (0,255))
        draw = True

When the mouse button is released, save the coordinates for the oval, along with the color that it was drawn with.

    elif event.type == pygame.MOUSEBUTTONUP:
        draw = False
        # print len(ovals) # (always ==1)
        completedOvals.append ((ovals[-1], OVAL_COLOR)) 

When we iterate through these completed ovals, draw them with the same color each time.

        for (completedOval, color) in completedOvals:
            pygame.draw.ellipse(windowSurface, color, completedOval)